package org.bouncycastle.asn1.x9;

import java.math.BigInteger;

import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.math.ec.ECFieldElement;

/**
 * class for processing an FieldElement as a DER object.
 */
public class X9FieldElement implements DEREncodable {
    private ECFieldElement f;

    public X9FieldElement(ECFieldElement f) {
        this.f = f;
    }

    public X9FieldElement(boolean fP, BigInteger q, ASN1OctetString s) {
        if (fP) {
            this.f = new ECFieldElement.Fp(q, new BigInteger(1, s.getOctets()));
        } else {
            throw new RuntimeException("not implemented");
        }
    }

    public ECFieldElement getValue() {
        return f;
    }

    /**
     * Produce an object suitable for an ASN1OutputStream.
     * 
     * <pre>
     *  FieldElement ::= OCTET STRING
     * </pre>
     * <p>
     * <ol>
     * <li>if <i>q</i> is an odd prime then the field element is processed as an Integer and converted to an octet string according to x 9.62 4.3.1.</li>
     * <li>if <i>q</i> is 2<sup>m</sup> then the bit string contained in the field element is converted into an octet string with the same ordering
     * padded at the front if necessary.</li>
     * </ol>
     */
    public DERObject getDERObject() {
        return new DEROctetString(f.toBigInteger().toByteArray());
    }
}
